SPY.HOUSE is a free service for analyzing and monitoring online advertising.
Advantages:
1) Access to 6 million creatives from 25 ad networks;
2) Search ads by keyword, domain, redirect;
3) Sort ads by popularity, life time, newness, number of impressions to select the best ones;
4) Search for landings and pre-landings by domain, keyword, word on the landing;
5) Determination of the best landing pages by the number of ads and lifetime.